Create new ones? Or install ones that exist already? Installing existing ones other people created is easy, making new ones is a bit harder.
For markings, people use the "UV guide" markings in a paint like program, image 512 pixels square.
Draw black where they don't want the colours to be, and transparent where they want the colour, so it appears.
Similar to how this is done
https://feral-heart.com/index.php?option=com_content&view=article&id=9&Itemid=16then you'd have to add it to the markings.cfg file. That's probably the hard part, when i look at the coding i know somewhat how it works but i can't explain it very well.
